721
FXUS65 KPSR 232000
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
100 PM MST SUN AUG 23 2026
KEY MESSAGES
- ISOLATED TO SCATTERED THUNDERSTORMS, SOME STRONG TO SEVERE, ARE
EXPECTED THIS EVENING ACROSS SOUTH-CENTRAL ARIZONA.
- INCREASINGLY LESS FAVORABLE CONDITIONS FOR THUNDERSTORMS WILL
DEVELOP STARTING MONDAY WITH VIRTUALLY NO CHANCES FOR RAIN FROM
TUESDAY THROUGH THE REST OF THE WEEK.
- HIGH TEMPERATURES WILL REACH OR EXCEED 110 DEGREES NEARLY EVERY
DAY THIS WEEK AND WILL BE NEAR DAILY RECORDS, WHILE MORNING
LOWS REMAIN UNUSUALLY WARM.
- EXTREME HEAT WARNINGS ARE IN EFFECT THROUGH SATURDAY WITH DAILY
MAJOR TO EXTREME HEATRISK.
SHORT TERM /TODAY THROUGH MONDAY/
SOME UPPER LEVEL JET SUPPORT AND MID-LEVEL GRAVITY WAVES HELPED
SPARK OFF A LINE OF HIGH-BASED SCATTERED SHOWERS AND STORMS
ACROSS SOUTHWEST AZ THIS MORNING. THIS ACTIVITY HAS SINCE WEAKENED
AND DISSIPATED. SURFACE-BASED MOISTURE HAS ALSO INCREASED ACROSS
SOUTHWEST AZ AND AREAS SOUTH OF I-8. DEW POINT TEMPERATURES AT
MIDDAY IN YUMA COUNTY TO WESTERN PIMA COUNTY WERE UP TO 65-75
DEGREES. THIS MOISTURE RETURN IN SOUTHERN AZ WILL LIKELY HELP
FUEL LATER AFTERNOON AND EVENING THUNDERSTORMS. OVERALL, MODEL
GUIDANCE STILL SUGGESTS THIS AFTERNOON THROUGH THIS EVENING
BECOMING A SOMEWHAT BUSY MONSOON PERIOD.
OUTSIDE OF SOUTHERN AZ, WHERE THE BEST MOISTURE RETURN WAS,
BOUNDARY LAYER CONDITIONS REMAIN SIMILAR TO THE PAST COUPLE OF
DAYS WITH SUB-OPTIMAL MOISTURE (MIXING RATIOS AROUND 8 G/KG) AND
LIMITED INSTABILITY (FEW HUNDRED J/KG MLCAPE). INITIALLY THROUGH
MUCH OF, IF NOT ALL OF, THIS AFTERNOON STORMS SHOULD FAVOR HIGHER
TERRAIN AREAS, INCLUDING PORTIONS OF LA PAZ COUNTY, AND IT MAY
EVEN LOOK LIKE IT WILL NOT BECOME ACTIVE AT ALL. HOWEVER, HI-RES
GUIDANCE CONTINUES TO SHOW THE BEST TIME PERIOD FOR ACTIVITY
ACROSS SOUTH-CENTRAL AZ COMING AROUND AND AFTER SUNSET. GUIDANCE
SHOWS STORMS BEING A BIT SLOWER TO DEVELOP IN PIMA COUNTY, BUT
WHEN THEY DO THEY DO THEY WILL HAVE THE BEST POTENTIAL TO BECOME
STRONG TO SEVERE, TAPPING INTO THE BEST MOISTURE AND INSTABILITY.
THE STORMS TO THE SOUTH THIS EVENING WILL THEN BE CAPABLE OF
PUSHING ONE OR MULTIPLE STRONG AND DUSTY OUTFLOWS NORTHWARD INTO
SOUTH-CENTRAL AZ, WHICH MAY THEN TRIGGER ADDITIONAL STORMS. SOME
HI-RES MODEL RUNS ALSO SUGGEST OUTFLOW COLLISIONS MAY OCCUR, WITH
OUTFLOWS ALSO FROM THE NORTH, BUT CONFIDENCE IN OUTFLOWS COMING
DOWN FROM NORTHERN AZ IS LOW. ADDITIONALLY, THERE ARE INDICATIONS
THE STORMS TO THE SOUTH MAY DEVELOP INTO AN MCV AND TRACK
NORTHWARD THROUGH PHOENIX THIS EVENING. STRONG TO LOCALLY SEVERE
WIND GUSTS WILL BE THE PRIMARY WEATHER HAZARDS, WITH VERY HIGH
DCAPE VALUES UP TO 1800-2000 J/KG. LOCALIZED FLASH FLOODING MAY
ALSO BECOME A THREAT WITH ANY SLOW-MOVING STORMS OR TRAINING OF
STORMS, WITH THE BEST POTENTIAL SOUTHWEST OF PHOENIX WHERE
MOISTURE WILL BE HIGHEST.
CONVECTIVE CHANCES FOR MONDAY ARE EVEN MORE UNCERTAIN AS GUIDANCE
GENERALLY SHOWS AT MOST A 10% CHANCE DESPITE MOISTURE AND
INSTABILITY BEING BETTER THAN TODAY. HOWEVER, SUBSIDENCE WILL BE
MUCH STRONGER ON MONDAY AS THE SUBTROPICAL RIDGE BEGINS TO MOVE
WESTWARD BACK INTO OUR REGION. WE WILL HAVE TO WAIT UNTIL TONIGHT
TO HAVE A BETTER IDEA ON THE STORM POTENTIAL FOR MONDAY, BUT IT
DOES SEEM TO BE CONSIDERABLY LOWER THAN THIS AFTERNOON/EVENING.
TEMPERATURES TODAY WILL AGAIN BE RIGHT NEAR RECORD HIGHS WITH
LOWER DESERT READINGS FROM 110-115 DEGREES. THE INCREASED BOUNDARY
LAYER MOISTURE EXPECTED FOR MONDAY SHOULD HOLD DAYTIME HIGHS DOWN
A BIT WITH NBM FORECAST HIGHS CURRENTLY BETWEEN 106-111 DEGREES,
BUT HEAT INDICES WILL MOSTLY MATCH WHAT ARE EXPECTED TODAY.
LONG TERM /TUESDAY THROUGH SATURDAY/
FORECAST ATTENTION TURNS AWAY FROM MONSOON STORM POTENTIAL AND
BACK TOWARD THE EXTREME HEAT CONDITIONS STARTING TUESDAY. THE
SUBTROPICAL HIGH CENTER WILL CONTINUE TO SHIFT WESTWARD INTO OUR
REGION INTO THE MIDDLE PART OF THE WEEK WITH THE CENTER LIKELY
SETTLING SOMEWHERE OVER SOUTHERN ARIZONA FROM WEDNESDAY THROUGH AT
LEAST FRIDAY OR SATURDAY. FORECAST H5 HEIGHTS ARE ALSO SHOWN TO
REACH 594-597DM FOR THE LATTER HALF OF THE WEEK WHICH PLACES IT
JUST SHY OF CLIMATOLOGICAL RECORDS FOR LATE AUGUST. NBM
TEMPERATURE GUIDANCE REMAINS QUITE CONSISTENT SHOWING HIGHS RISING
INTO A 112-116 DEGREE RANGE FOR THE LATTER HALF OF THIS WEEK AS
CONDITIONS DRY OUT. DAILY TEMPERATURE RECORDS IN PHOENIX WILL
CONTINUE TO BE IN JEOPARDY THROUGH THE ENTIRE WEEK, BUT ARE LIKELY
TO FALL SHORT IN YUMA AND EL CENTRO. ONCE THE HIGH CENTER MOVES
OVERHEAD BY WEDNESDAY, RAIN CHANCES WILL ESSENTIALLY GO TO 5% OR
LESS. AS OF NOW, CONDITIONS FOR ANY MONSOON STORM ACTIVITY DO NOT
LOOK GOOD THROUGH NEXT WEEKEND.
AVIATION
UPDATED AT 1800Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
THE POTENTIAL FOR MULTIPLE OUTFLOW BOUNDARIES RESULTING IN SUDDEN,
GUSTY WIND SHIFTS THIS EVENING, AS WELL AS SHRA/TSRA DEVELOPING IN
THE PHOENIX AIRSPACE PRESENTS THE GREATEST WEATHER ISSUE DURING
THIS TAF PERIOD. WINDS WILL FAVOR E/SE LATE THIS MORNING FOLLOWED
LIKELY BY A PERIOD OF VRB WINDS BEFORE SHIFTING OUT OF A
PREVAILING WESTERLY DIRECTION BY 20-22Z THIS AFTERNOON. TS OVER
THE NORTHERN AND EASTERN AZ HIGH TERRAIN ARE LIKELY TO SEND A
FIRST OUTFLOW TOWARDS THE LOWER ELEVATIONS LATE THIS
AFTERNOON/EARLY THIS EVENING, WHICH WOULD CAUSE A SUDDEN WIND
SHIFT OUT OF A N/NE'RLY DIRECTION. A CLUSTER OF STRONG STORMS IS
THEN EXPECTED TO DEVELOP OVER WESTERN PIMA, SOUTHWESTERN PINAL,
AND/OR SOUTHERN MARICOPA COUNTIES THIS EVENING, WHICH WOULD
LIKELY SEND A SECOND, STRONGER OUTFLOW ACROSS THE TERMINALS FROM
THE S/SW. THIS SECOND OUTFLOW MAY CAUSE TEMPORARY SURFACE VIS
RESTRICTIONS DUE TO BLOWING DUST AND MORE PROLONGED SLANTWISE VIS
ISSUES IF RAIN DOES NOT FOLLOW. CHANCES FOR SHRA/TSRA REMAIN
AROUND 20-30% ACROSS THE TERMINALS THIS EVENING, AND SO HAVE
INCLUDED THIS IN PROB30 GROUPS BETWEEN 04-07Z. THE WIND FORECAST
IS VERY LOW CONFIDENCE THIS EVENING INTO THE OVERNIGHT HOURS DUE
TO THE POSSIBLE INFLUENCE OF MULTIPLE OUTFLOWS, AND GUSTY, ERRATIC
WINDS ARE EXPECTED IF SHRA/TSRA DEVELOP NEAR THE TERMINALS. CLOUD
BASES WILL REMAIN MOSTLY ABOVE 10 KFT AGL THROUGH THE PERIOD.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO MAJOR AVIATION CONCERNS ARE EXPECTED THROUGH THE NEXT 24 HOURS.
WINDS AT KIPL WILL FAVOR SOUTHEASTERLY DIRECTIONS. TS ACTIVITY
OVER THE BAJA SPINE MAY SEND AN SOUTHWESTERLY OUTFLOW INTO KIPL BY
THE LATE AFTERNOON HOURS, WITH A LESS THAN 20% CHANCE FOR DIRECT
TS IMPACTS. KBLH WILL SWING BETWEEN SOUTH TO SW'RLY WINDS, WITH
OCCASIONAL GUSTS TO AROUND 20 KTS. THERE IS ALSO A LOW CHANCE
(LESS THAN 10%) FOR SHRA/TSRA CONDITIONS AT KBLH, PARTICULARLY
DURING THE OVERNIGHT PERIOD. FEW-SCT MID AND HIGH LEVEL CLOUD
DECKS WILL BE COMMON THROUGH THE PERIOD.
FIRE WEATHER
HOT TEMPERATURES WILL PREVAIL THROUGH THE ENTIRE WEEK WITH SHOWER
THUNDERSTORM CHANCES MAINLY TODAY AND POSSIBLY MONDAY. STRONG
GUSTY WINDS WILL BE POSSIBLE LATE THIS AFTERNOON AND EVENING WITH
ANY THUNDERSTORMS, WHILE CHANCES FOR WETTING RAINS WILL REMAIN
BELOW 20%. MINIMUM RHS WILL IMPROVE THROUGH MONDAY WITH READINGS
OF 15-25% TODAY AND 20-30% MONDAY, BEFORE DROPPING BACK INTO THE
TEENS INTO THE MIDDLE PART OF THE WEEK. TEMPERATURES WILL BE
AROUND 5-10 DEGREES ABOVE NORMAL, WITH LOWER DESERT HIGHS
ECLIPSING 110 DEGREES NEARLY EVERY AFTERNOON. OUTSIDE OF
THUNDERSTORM OUTFLOW WINDS, WINDS WILL FOLLOW THE TYPICAL DIURNAL
TENDENCIES WITH SOME MODEST AFTERNOON UPSLOPE GUSTINESS.
CLIMATE
RECORD HIGHS:
DATE PHOENIX YUMA EL CENTRO
---- ------- ---- ---------
AUG 23 114 IN 2011 115 IN 2011 116 IN 1969
AUG 24 115 IN 2020 119 IN 1985 117 IN 1985
AUG 25 113 IN 2011 116 IN 1962 117 IN 1962
AUG 26 117 IN 2011 115 IN 2020 115 IN 1981
AUG 27 114 IN 2023 120 IN 1981 117 IN 1981
AUG 28 117 IN 2023 118 IN 2023 117 IN 2009
AUG 29 116 IN 2023 117 IN 1954 117 IN 2005
PSR WATCHES/WARNINGS/ADVISORIES
AZ...EXTREME HEAT WARNING UNTIL 8 PM MST SATURDAY FOR AZZ530>555-559-
560.
CA...EXTREME HEAT WARNING UNTIL 8 PM PDT SATURDAY FOR CAZ562-565>567-
569-570.
SHORT TERM...BENEDICT/KUHLMAN
LONG TERM...KUHLMAN
AVIATION...WHITTOCK
FIRE WEATHER...KUHLMAN
CLIMATE...18/KUHLMAN
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